1. Field of the Invention
The present invention relates to an ink jet printing method and ink jet printer. More particularly, the present invention relates to an ink jet printing method and ink jet printer capable of removing choking of ink or other failure in a printing head.
2. Description Related to the Prior Art
An ink jet printer is known, and includes an ink jet printing head, which includes a group of nozzles for ejecting ink to recording material to print an image thereto. If the ink jet printer is repeatedly used, choking of ink is likely to occur in the nozzles. It is likely that an ejected amount of ink decreases. Furthermore, no ink may be ejected. This causes unevenness in color or density to occur in a printed image.
In general, an operator observes the printed image, and if there are streaks with unevenness in color or density, changes over the ink jet printer to a head cleaning mode. The printer is cleaned to eliminate the choking of ink or abnormality in a direction of ejecting the ink. In a cleaning process, ink are caused to flow out of the nozzles at a high flow rate. Also, the nozzles are sucked externally to remove choking ink. Furthermore, the periphery of the nozzles is wiped. It is, however, likely that an operator discovers the choking of ink too late. Images may be printed at a low quality due to the failure. If the printer is used by a user at home, no serious problem occurs even with drop in the image quality. However, if the printer is used commercially at a printing shop, failure in operation of the nozzles may cause serious problem due to occurrence of a great number of failing prints to be produced.
In view of the foregoing problems, an object of the present invention is to provide an ink jet printing method and ink jet printer capable of removing failure in a printing head.
In order to achieve the above and other objects and advantages of this invention, in an ink jet printing method, a printing head is used, and has plural nozzles for ejecting ink. At least one image is printed to recording material with the printing head. Before or after printing the image, the printing head is cleaned by driving at least part of the plural nozzles.
An ink jet printer of the invention has a printing head including plural nozzles arranged in a main scan direction, for ejecting ink. A moving mechanism moves one of the printing head and recording material relative to a remainder thereof in a sub scan direction, to print at least one image to the recording material. A controller operates before or after printing the image, to clean the printing head by driving at least part of the plural nozzles.
The at least one image is plural images. The controller cleans the printing head in a beginning or ending position of respectively the plural images, the printing head prints a cutting indicia to the recording material upon being cleaned, and the cutting indicia is adapted to separating the images.
The recording material is continuous recording sheet or a recording sheet strip.
Furthermore, an indicia sensor detects the cutting indicia. A cutter cuts the recording material at the cutting indicia in response to detection of the cutting indicia, to obtain prints having respectively the images.
The printing head prints a sorting indicia to the recording material upon being cleaned in a beginning or ending position of one series of the plural images, the sorting indicia being different from the cutting indicia in at least one of a width, length, position, color and shape. The indicia sensor further detects the sorting indicia. Furthermore, a sorter is actuated in response to detection of the sorting indicia, for grouping the prints by the series of the images.
In a preferred embodiment, the sorting indicia is different in a position from the cutting indicia with reference to a direction crosswise to arrangement of the plural images.
In another preferred embodiment, the sorting indicia is different from the cutting indicia in a size with reference to the sub scan direction.
In a further preferred embodiment, at least one of the cutting indicia and the sorting indicia includes plural colored portions arranged in a patterned manner.
The cutting indicia includes the plural colored portions arranged at a first pitch, the sorting indicia includes the plural colored portions arranged at a second pitch different from the first pitch.
In a preferred embodiment, a remaining one of the cutting indicia and the sorting indicia includes a single colored portion.
In another preferred embodiment, the plural colored portions are dots.
In an additional preferred embodiment, the plural colored portions are stripes.
In a preferred embodiment, the ink is ink of first to Nth colors, the images are full-color images. The plural nozzles are arranged in first to Nth groups for ejecting the ink of respectively the first to Nth colors. The controller drives one of the first to Nth groups at each time of printing one of the plural images, to print first to Nth cutting indicia cyclically in respectively the first to Nth colors.
In another preferred embodiment, the sorting indicia is different in a position from the cutting indicia.
The plural nozzles are grouped in first to Pth groups with reference to the main scan direction. The controller drives one of the first to Pth groups at each time of printing one of the plural images, to print first to Pth cutting indicia cyclically, the first to Pth cutting indicia being offset from one another with reference to the main scan direction.
In still another preferred embodiment, the moving mechanism is a head carriage for moving the printing head in the sub scan direction, for image printing in a belt shape. Furthermore, a second moving mechanism moves one of the head carriage and the recording material relative to a remainder thereof in the main scan direction, to print the image.